These errors are occurring because the include for the cart is missing. You need to ensure that you have the eCart include line of code above these calls:
<?php
//WA eCart Include
require_once("WA_eCart/houstonWood_PHP.php");
?>
If you already have this code or get the same error it would indicate that the file is not present, make sure it gets uploaded to the WA_eCart folder on your server.